The Army shrink who killed 13 at Fort Hood “walked right through a gaping hole” in the federal system to keep guns away from terrorists, Sen. Charles Schumer charged yesterday.

Army psychiatrist Maj. Nidal Malik Hasan bought a gun at a Texas store in August, even though the Joint Terrorism Task Force had investigated him for terrorist ties. The FBI didn’t alert its own terrorism unit about the gun sale.

“He walked right through a gaping hole in the federal system,” Schumer said.